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Publication numberUS4433275 A
Publication typeGrant
Application numberUS 06/269,592
Publication dateFeb 21, 1984
Filing dateJun 2, 1981
Priority dateJun 3, 1980
Fee statusPaid
Also published asDE3162948D1, EP0041382A1, EP0041382B1
Publication number06269592, 269592, US 4433275 A, US 4433275A, US-A-4433275, US4433275 A, US4433275A
InventorsRyoji Imazeki, Etsuo Yamazaki
Original AssigneeFujitsu Fanuc Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Three-dimensional tracer control system
US 4433275 A
Abstract
A three-dimensional tracer control system which is provided with an integration circuit for integrating the difference between a Z-axis direction displacement signal and a reference displacement signal and an adder for adding together the above-mentioned difference and the output from the integration circuit. The trace velocity in the Z-axis direction is controlled by the output from the adder, by which it is possible to perform tracing, with the Z-axis direction displacement signal and the reference displacement signal held nearly equal to each other; consequently, machining accuracy is increased.
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Claims(2)
What is claimed is:
1. A three-dimensional tracer control system which traces the configuration of a model based on direction displacement signals from a tracer head, said system comprising:
said tracer head providing X- , Y- and Z-axis direction displacement signals as said direction displacement signals;
X-Y means for controlling the tracing of said tracer head in the X-Y plane according to said X- and Y-axis direction displacement signals and a desired value of a function thereof;
an integration circuit for integrating the difference between said Z-axis direction displacement signal and a desired value thereof;
an adder for adding together said difference and the output from said integration circuit; and
means for controlling the trace velocity in the Z-axis direction in accordance with the output signal from said adder.
2. The system of claim 1, said X-Y means controlling the tracing of said tracer head in the X-Y plane according to the positive square root of the sum of the squares of said X- and Y-axis direction displacement signals and a desired value therefor.
Description
BACKGROUND OF THE INVENTION

The present invention relates to a three-dimensional tracer control system which permits a highly accurate machining operation.

There has heretofore been put to practical use a three-dimensional tracer control system that traces the configuration of a model in the X-Y plane by X- and Y-axis direction displacement signals available from a tracer head and controls the trace velocity in the Z-axis direction by a Z-axis direction displacemnt signal. FIG. 1 illustrates in block form an example of such a conventional system. In FIG. 1, reference numeral 1 indicates a tracer head; 2 designates a stylus; 3 identifies a displacement resultant circuit; 4 and 9 denote adders; 5 and 6 represent velocity components arithmetic circuits; 7 shows a distributing circuit; 8 refers to a displacement direction index circuit; 10 indicates an amplifier; 11 to 13 designate drivers; and 14 to 16 identify motors.

The tracer head 1 yields displacement signals εx, εy and εz corresponding to displacement of the stylus 2 in the X- , Y- and Z-axis directions. The displacement signals εx and εy are provided to the displacement resultant circuit 3 and the displacement direction index circuit 8 and the displacement signal εz is applied to the adder 9. The displacement resultant circuit 3 obtains a resultant displacement signal ε=√εx 2y 2 from the displacement signals εx and εy and applies it to the adder 4. The displacement direction index circuit 8 derives displacement direction signals sin θ and cos θ from the displacement signals εx and εy and provides them to the distributing circuit 7.

The adder 4 detects a difference Δε=ε-ε0 between the resultant displacement signal ε from the displacement resultant circuit 3 and a reference displacement signal ε0. The velocity components arithmetic circuits 5 and 6, which are supplied with the output from the adder 4, derive therefrom a normal-direction velocity signal VN and a tangential-direction velocity signal VT, respectively, which are provided to the distributing circuit 7. Based on the normal-direction velocity signal VN, the tangential-direction velocity signal VT and the displacement direction signals sin θ and cos θ, the distributing circuit 7 produces velocity command signals in the X- and Y-axis directions by which the difference Δε between the resultant displacement signal ε and the reference displacement signal ε0 is reduced to zero. The velocity command signals are applied to the drivers 11 and 12, which drive the motors 14 and 15 in response to the velocity command signals.

The adder 9, which is supplied with the displacement signal εz, detects a difference εzz0 between it and a reference displacement signal εz0. The difference εzz0 thus obtained is applied via the amplifier 10 to the driver 13, causing it to drive the motor 16 which performs the Z-axis control. By driving the motors 14 to 16 in the manner described above, the tracer head 1 and a cutter (not shown) are fed together to achieve machining operations of a work (not shown).

Now, consider tracing of such a slope as shown in FIG. 3 which has an angle of inclination α. In this case, assuming that the trace velocity in the X-Y plane is VXY, it is necessary that the trace velocity VZ in the Z-axis direction be as follows:

VZ =VXY Ětan α                    (1)

In the conventional three-dimensional tracer control system, since the trace velocity VZ in the Z-axis direction is in proportion to the difference (εzz0) between the displacement signal εz and the reference displacement signal εz0 in the Z-axis direction, the Z-axis velocity VZ is given by the following expression (2):

VZ =K(εzz0)              (2)

where K is a proportional constant.

From expressions (1) and (2), the displacement signal εz in the Z-axis direction becomes as follows: ##EQU1##

As is evident from expression (3), the displacement signal εz in the Z-axis direction varies with a change in the feed rate VXY in the X-Y plane or the angle of inclination α, resulting in variations in machining accuracy. In other words, the prior art tracer control system has the defects of inaccurate machining operations and degraded traceability in the X-Y plane.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a three-dimensional tracer control system with which it is possible to obtain a high degree of machining accuracy.

Another object of the present invention is to provide a three-dimensional tracer control system which permits tracing in the state in which the displacement signal and the reference one in the Z-axis direction are held substantially equal to each other.

Briefly stated, the three-dimensional tracer control system of the present invention is provided with an integration circuit for integrating the difference between the displacement signal and the reference one in the Z-axis direction, and an adder for adding together the abovesaid difference and the output from the integration circuit and controls the trace velocity in the Z-axis direction in accordance with the output from the adder.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a prior art example;

FIG. 2 is a block diagram illustrating an embodiment of the present invention; and

FIG. 3 is a diagram explanatory of the operation of each of the prior art example shown in FIG. 1 and the embodiment of the present invention depicted in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The embodiment of the present invention illustrated in FIG. 2 differs from the prior art example of FIG. 1 in the provision of an integration circuit 21 for integrating the output (εzz0) from the adder 9 and an adder 22 for adding together the output εzI =∫(εzz0)dt from the integration circuit 21 and the output from the adder 9. In FIG. 2 the parts corresponding to those in FIG. 1 are identified by the same reference numerals.

Accordingly, in this embodiment the trace velocity VZ in the Z-axis direction is given by

VZ =K(εzz0zI) (4)

where K is a proportional constant.

Assuming that the slope such as shown in FIG. 3 is traced at the velocity VXY (which is the trace velocity in the X-Y plane), it is necessary that the trace velocity VZ in the Z-axis direction be such as given by expression (1), as mentioned previously; accordingly, the displacement signal εz in the Z-axis direction becomes, from expressions (1) and (4), as follows: ##EQU2## when εzz0 ≠0, the output εzI =∫(εzz0)dt from the integration circuit 21 approaches (VXY Ětan α)/K so that εzI =(VXY Ětan α)/K; therefore, tracing can be conducted with εzz0, thus increasing the degree of machining accuracy.

As has been described in the foregoing, the present invention is provided with the integration circuit, for integrating the difference between the displacement signal and the reference one in the Z-axis direction, and the adder for adding together the abovesaid difference and the output from the integration circuit, and which controls the trace velocity in the Z-axis direction in accordance with the output from the adder, so that tracing can be performed with the displacement signal and the reference one in the Z-axis direction held substantially equal to each other. Accordingly, the present invention possesses the advantage of increased machining accuracy.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4534685 *Apr 9, 1982Aug 13, 1985Fanuc Ltd.Tracer control system
US4586124 *Dec 21, 1983Apr 29, 1986Starkstrom Gummersbach GmbhDevice for regulating linear motion
US4641069 *Nov 11, 1983Feb 3, 1987Fanuc LtdPlural motor changeover control system
US4982336 *Oct 26, 1988Jan 1, 1991Fanuc, Ltd.Tracer control apparatus
US5128880 *May 11, 1990Jul 7, 1992Foot Image Technology, Inc.Foot measurement and footwear sizing system
US5195030 *May 11, 1990Mar 16, 1993Foot Image Technology, Inc.System and method of foot shape imaging and overlay
US5206804 *May 11, 1990Apr 27, 1993Foot Image Technology, Inc.Footwear visual image cataloging and sizing
US5237520 *May 29, 1992Aug 17, 1993Foot Image Technology, Inc.Foot measurement and footwear sizing system
US5339252 *Jan 7, 1993Aug 16, 1994Foot Image Technology, Inc.Integrated system for foot measurement, last and footwear manufacture
Classifications
U.S. Classification318/578, 318/575, 318/625
International ClassificationB23Q35/123, G05D3/00, B25J9/18, B23Q35/12
Cooperative ClassificationB23Q35/123
European ClassificationB23Q35/123
Legal Events
DateCodeEventDescription
Aug 7, 1995FPAYFee payment
Year of fee payment: 12
Aug 19, 1991FPAYFee payment
Year of fee payment: 8
Apr 6, 1987FPAYFee payment
Year of fee payment: 4
Jun 2, 1981ASAssignment
Owner name: FUJITSU FANUC LIMITED, NO. 5-1, ASAHIGAOKA 3-CHOME
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:IMAZEKI, RYOJI;YAMAZAKI, ETSUO;REEL/FRAME:003891/0390
Effective date: 19810521